Hey BillP, it's your turn to chime in!

[Boomyal]

...thinning epoxy resin. I'm getting ready to purchace the plywood for my floor. AB, I think is the preferred non-marine premium grade plywood. I want to soak it in the very most penetrating epoxy resin without spending $75.00 a gallon to do it (cpes). I know that it has been talked about before but maybe we can outline, for all eternity, a definitive formula for accomplishing this goal.<br /><br />A) What to thin it with?<br />B) What to thin it by? (%)<br />C) When to thin it, before or after the catalyst?<br />D) Any necessary adjustment in catalyst necessary considering the addition of thinning agent?

 

[Chris1956]

Re: Hey BillP, it's your turn to chime in!

Boomyal, I'n not sold on the necessity of using epoxy on new plywood flooring. I think Poly will work just fine. I would use epoxy for fixing serious cracks and holes in the hull, and high strength stuff like new transoms. <br /><br />In your case, I would cut the plywood to size, brush its bottom and edges with poly resin (use a bit less hardener so it penetrates better), put poly saturated cloth strips over the stringers and frames, and screw the floor into the framing with SS screws. I would then cover the top of the floor with resin, and cloth. Run the cloth up the sides of the hull, and use 3+ layers of cloth at the hull/floor joint. Give it about 4 coats of poly resin and have a beer!.

 

[ThomWV]

Re: Hey BillP, it's your turn to chime in!

I would not use polyester resin anywhere directly on wood. Simply put it does not bond well. I would not thin the epoxy at all, why would you? Just apply it with a roller using a slow set hardner and let it kick. I can tell you that I have used acetone to thin epoxy (doesn't matter if you add it before or after the catalyst is added) and at about 30% (just a guess) the stuff will harden but it will not get rock hard, it becomes of a consistance about equal to a soft art-gum rubber eraser. At any rate I don't think you gain anything at all by tryng to thin it. I don't think it will 'soak in' any better and even if it did I don't see how this is of any benefit to you. Once the outside and edges are sealed what difference does it make that you managed to get some of it to soak all the way to the core? Its no stronger and its no better protected from the elements.<br /><br />Thom

 

[Realgun]

Re: Hey BillP, it's your turn to chime in!

Sorry but Polyester resin will not stop water at all. Gel cote does two thing for poly resin-<br />1. Stops UV light.<br />2. Stop water penetration.<br /><br />My suggestion is use regular epoxy and use the slowest cureing type. This allows the epoxy to penetrate deep in the wood. Also use two cotes this will seal the wood much better.<br /><br />On my boat the plywood that was polyed in comes right out the poly never penetrated at all.<br /><br />True it is more expensive but if you really want it to never get wet and rot use the two part epoxy.

 

[JasonJ]

Re: Hey BillP, it's your turn to chime in!

Hate to burst the bubble, but gelcoat is basically tinted poly. If wood gets wet, then the poly was not applied right, plain and simple. Most mistakes are made in the cataylist mix, it kicks off too quick, and you end up with the poly just on the surface. Go for a slow kick and it will penetrate adequately. Yes, epoxy rocks, and would be the first choice if wallet allows, but poly is not as bad as some would claim. I like to coat the wood liberally with poly mixed with less cataylist so it takes longer to kick off, so it soaks in better. You will never get any product, be it poly or epoxy to soak to the core, but you can get enough saturation to protect the wood. Those who say poly does not bond or penetrate must never have had to remove an original transom before. I am here to tell you that you end up ripping the ply off in layers and have to grind the last few layers of ply off of the shell, not pleasant.<br /><br />I too don't know that you need to thin the epoxy. Hopefully BillP will chime in, he is the one who knows the deal with thinning epoxy and poly.

 

[Boomyal]

Re: Hey BillP, it's your turn to chime in!

Ok BillP, Jason says you da man! Gettin lots of opinions here, now it's your turn. The rot doctor says their CPES will soak into wood/plywood as far as water would, thereby protecting any wood that would become exposed. Problem is that CPES is waaaaaay too expensive. I don't mind the added cost of epoxy over poly but I want maximum penetration for less than $75.00 a gallon.

 

[crab bait]

Re: Hey BillP, it's your turn to chime in!

a deep soak is ,yeah, the best.. the deeper the better.. but epoxy in the shade ( of coarse , always should be in the shade ) is very adequate..<br /><br />i always go with 2 coats,, not because the plans/instructions say so,, i do it because the first coat wicks in to much..a 2 coat is required..<br /><br />everything i ever read on epoxy says not to thin.. OR BUMP or LOWER hardener ratio.. <br /><br />not sayin' it can't be thinned... i just really never seen the need an never had to & the 'brass' it do it.. <br /><br />IF'N IT DON'T WORK... WHAT A MESS...

 

[JasonJ]

Re: Hey BillP, it's your turn to chime in!

Crab, talk about a mess. I watched a guy mix epoxy with what he thought was the hardener and apply. I looked at his "hardener" and he had used a small can of gelcoat instead of the hardener. It was a stringy nasty stinky mess to clean up...

 

[BillP]

Re: Hey BillP, it's your turn to chime in!

I ain't know experrt on this stuff but done sum of it a few tymes and been arounde long enough to see what happens yrs latter. Affter a few demolitions on old boats you learn fact from fiction. Like Jason sez, poly applied correctly is very tenacious on ply. It needs to be thinned with styrene and done in several coats for the best job. Acetone works as a thinner too but technically isn't made specifically as a "poly thinner" like styrene is. <br /><br />I HAVE used poly for coating exterior ply and had success but use only epoxy now. I thin epoxy up to 10% with acetone and it works ok. <br /><br />Like already mentioned, you can slow poly kicking time down with different hardener ratios but epoxy has to be mixed exact. I get more application time with either type by chilling the resin first and then starting the kick with a heat gun.<br /><br />My best results for coating ply are done by using a squeege to apply the resin and pressing hard into the wood. Do this in the thinnest coat possible. If you do it in thick coats the ply will suck resin and be dry in some areas and "wet" in others...the surface will be pock marked and irregular (rollers do this the worst are my last preference). Several thin coats (3-4 for me usually) fill all the grain and don't leave a thick layer in areas that can crack off. Most important if using poly and a non issue with epoxy (but wastes resin).<br /><br />Here is an easy home brew test that will give "in your face" results on coating ply. With any type resin...do a thinned sample and a non thinned sample on your ply. See which peels off and which pulls grain with it. There is no comparison in pull strengh between the two.<br /><br />About advertising that says thin epoxy saturates as deep as water does...if the resin is that thin is isn't strong. IF resin WAS that strong we would be seeing it in micro thin glass jobs in high tech applications. We're not seeing that ANYWHERE are we? I don't believe the advertising and don't believe the resin restores strength down deep as advertised.

 

[Boomyal]

Re: Hey BillP, it's your turn to chime in!

Originally posted by BillP:<br /> About advertising that says thin epoxy saturates as deep as water does...if the resin is that thin is isn't strong. IF resin WAS that strong we would be seeing it in micro thin glass jobs in high tech applications. We're not seeing that ANYWHERE are we? I don't believe the advertising and don't believe the resin restores strength down deep as advertised.

The object and claim of CPES, BillP, is not for strength. It is to render the woodfibers impervious to rot. It doesn't need to add strength to accomplish that. That is what I would hope to accomplish using less expensive thinned resin. I could always overcoat it with unthinned resin afterwords.

 

[BillP]

Re: Hey BillP, it's your turn to chime in!

I agree if you are talking treating good wood to seal it, but restoring strength to rotten wood is a different story. My response was in regard to advertising that says strength is restored and penetration deep. I've sampled various products over the years on rotten test samples and then cut them up. They have only performed on the surface where the eye can see. Cutting them up shows a different story.